UVALive 4670 (AC自动机)

题目链接:点击这里

题意:按照顺序输出在文本串中出现的次数最多的模式串.

水题,直接跑AC自动机,记录每一个模式串的次数就好了.

#include <bits/stdc++.h>
using namespace std;
#define maxn 511111
#define maxm 1111111

char str[155][77];
int n;
char a[maxm];
struct trie {
    int next[maxn][26], fail[maxn], end[maxn];
    int num[maxn];//每个单词出现的次数
    int f[maxn];//每个节点对应的单词编号
    int root, cnt;
    int new_node () {
        memset (next[cnt], -1, sizeof next[cnt]);
        end[cnt++] = 0;
        return cnt-1;
    }
    void init () {
        cnt = 0;
        root = new_node ();
        memset (num, 0, sizeof num);
        memset (f, -1, sizeof f);
    }
    void insert (char *buf, int pos) {//字典树插入一个单词
        int len = strlen (buf);
        int now = root;
        for (int i = 0; i < len; i++) {
            int id = buf[i]-'a';
            if (next[now][id] == -1) {
                next[now][id] = new_node ();
            }
            now = next[now][id];
        }
        end[now]++;
        f[now] = pos;
    }
    void build () {//构建fail指针
        queue <int> q;
        fail[root] = root;
        for (int i = 0; i < 26; i++) {
            if (next[root][i] == -1) {
                next[root][i] = root;
            }
            else {
                fail[next[root][i]] = root;
                q.push (next[root][i]);
            }
        }
        while (!q.empty ()) {
            int now = q.front (); q.pop ();
            for (int i = 0; i < 26; i++) {
                if (next[now][i] == -1) {
                    next[now][i] = next[fail[now]][i];
                }
                else {
                    fail[next[now][i]] = next[fail[now]][i];
                    q.push (next[now][i]);
                }
            }
        }
    }
    int query (char *buf) {
        int len = strlen (buf);
        int now = root;
        for (int i = 0; i < len; i++) {
            int id = buf[i]-'a';
            now = next[now][id];
            int tmp = now;
            while (tmp != root) {
                if (end[tmp]) {
                    num[f[tmp]] += end[tmp];
                }
                tmp = fail[tmp];//沿着失配边走
            }
        }
        int Max = 0;
        for (int i = 1; i <= n; i++) {
            Max = max (Max, num[i]);
        }
        printf ("%d\n", Max);
        for (int i = 1; i <= n; i++) if (num[i] == Max) {
            printf ("%s\n", str[i]);
        }
        return 0;
    }
}ac;


int main () {
    while (scanf ("%d", &n) == 1 && n) {
        ac.init ();
        for (int i = 1; i <= n; i++) {
            scanf ("%s", str[i]);
            ac.insert (str[i], i);
        }
        ac.build ();
        scanf ("%s", a);
        ac.query (a);
    }
    return 0;
}